By default, your box will be actively protected from the moment you boot up.

Once detected any threats, you could view the details in the Protection History section.

What can you do if the Unable to block this app message displays in Windows Security?

check Windows Defender Offline scan and hit Scan now

To remove this potentially unwanted app, go to Windows App & features page and remove the app.

Without further ado, lets dive right in!

Heres how to do it:

Step 1.

hit Browse to add the problematic program to the list

In the options menu, locateUpdate & Securityand hit it.

Head toWindows Security>Virus & threat protections>Scan options.

TickWindows Defender Offline scanand hitScan nowto start the scanning.

right-click on the malicious program and select End task

Solution 2: Block the Program Through Windows Firewall Manually

Step 1.

Typecontrol panelin the search bar and hitEnter.

Navigate toSystem and Security>Windows Defender Firewall.

right-click on the problematic app and select Uninstall

In the left pane, click onAllow an app or feature through Windows Defender Firewall.

Tap onChange settingsand scroll down to find the problematic program.

If it isnt listed, click onAllow another app> hitBrowse> choose the program > hitAdd.

Then, confirm the checkbox next to the programs name is unchecked.

After that,Windows Security unable to block this appmust be gone.

Move 1: Find out the Problematic Program

Step 1.

TypeWindows Securityin the search bar and hitEnter.

Tap onVirus & threat protection>Protection history.

Find theUnable to block this appand punch it.

Click onYesin theUser Account Controlwindow.

Now, you’re free to find the malicious software.

Move 2: Terminate Related Tasks

Step 1.

PressCtrl+Shift+Escaltogether to launchTask Manager.

Locate the program you wish to remove and right-punch it to selectEnd task.

Move 3: Uninstall It Manually

Step 1.

Right-tap on theStartmenu and selectRun.

Inputappwiz.cpland hitEnterto launchPrograms and Features.

Now, you’ve got the option to see a list of programs installed on your PC.

Right-tap on the problematic program and selectUninstall.

Confirm this operation and follow the uninstallation wizard to finalize the uninstallation.

Final Words

Thats all the information about Windows Defender unable to block this app.

Also, the importance of data backup cannot be neglected.

To do this job, try MiniTool ShadowMaker to back up anything important on your machine.